Re: construction without fasteners

... I recommend against stainless--they are harder to use, and don t offer much in most applications for Michalak-style boats. But if you got em, you won t be

Message 1 of 21
, Nov 1, 2007

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Ray wrote:

> True, but on the other hand, drywall screws are cheaper than stainless
> and reusable as temporary fasteners, and even if you use stainless
> screws, you still have to putty the heads to get a smooth hull.

I recommend against stainless--they are harder to use, and don't offer
much in most applications for Michalak-style boats. But if you got 'em,
you won't be much harmed by their use.

Drywall screws may be reusable, but they mangle up the wood a lot more
than they need to, and fairing the holes is, in fact, quite a job.

> Of the disadvantages of fasteners, he says:
> 1/ Fasteners are expensive

It's all relative. All the silicon bronze ring nails you'd need for,
say, a Philsboat should cost you less than $18 at Jamestown Distributors
(one pound of 3/4"). Cheaper if you use copper.

> 2/ Fasteners often make the boat a little bit harder to fair

Not really, considering the offset of fairing the marks made by either
the temporary drywall screws, or even the clamps used in place of any
fastening.

> 3/ Over time fasteners may move a little, cracking the paint that
> covers their heads and allow moisture to get in.

The paint line can separate between the nail head and the surface of the
wood, a very small amount. The swelling of the wood into the annular
rings provides a seal equal to most paints--it's not really an issue.

> 4/ A glued structure has a waterproof glue line between parts.
> Fasteners penetrate the waterproof joins.

This is sorta true, but not true if your fastener goes in while the glue
is wet. And your fastener *should* be going in when the glue line is
wet. Otherwise, what are you doing?

> 5/ Fasteners can make repairs difficult - where fasteners are
> eliminated from the structure and part of the boat can be cut, planed
> or sawn without risk of damaging tools

True enough, although bronze and copper are only a modest hindrance.

> I'd never considered points 3 and 4, but they make sense to me.
> Another issue is that a glue joint spreads stresses over the largest
> possible area, whereas fasteners tend to concentrate stresses.

This is actually not correct. Keep in mind that a ring nail spreads out
stresses compared to a glue line. A glue line puts stresses in only one
(or two) dimensions, whereas the fastener adds a second (or third)
dimension. This can be a real boon, particularly when you're attaching
a frame/bulkhead to the hull (which was the original situation that
started this discussion).

In short, in vessels designed with solid lumber/plywood joints,
fasteners can be an *excellent* strategy. They are no replacement in
joints designed for stitch-and-glue, but I don't think anyone was
recommending it.

-Chris

rhaldridge

... It s probably one of those personal things, but I didn t find it to be so. In other projects, when I used ring nails and screws, the holes were just as

> Drywall screws may be reusable, but they mangle up the wood a lot more
> than they need to, and fairing the holes is, in fact, quite a job.

It's probably one of those personal things, but I didn't find it to be
so. In other projects, when I used ring nails and screws, the holes
were just as big, because nails and screws should be set below the
surface, but the fairing putty tended to pop off sometimes because it
didn't get much of a grip on the heads. The trick to fairing the
empty screw holes, I find, is to use a low-density filler and mound it
up a bit. It only takes a second with the orbital sander to cut them
level.

>
> > Of the disadvantages of fasteners, he says:
> > 1/ Fasteners are expensive
>
> It's all relative. All the silicon bronze ring nails you'd need for,
> say, a Philsboat should cost you less than $18 at Jamestown

Distributors

> (one pound of 3/4"). Cheaper if you use copper.
>
>
> > 2/ Fasteners often make the boat a little bit harder to fair
>
> Not really, considering the offset of fairing the marks made by either
> the temporary drywall screws, or even the clamps used in place of any
> fastening.
>
> > 3/ Over time fasteners may move a little, cracking the paint that
> > covers their heads and allow moisture to get in.
>
> The paint line can separate between the nail head and the surface of

the

> wood, a very small amount. The swelling of the wood into the annular
> rings provides a seal equal to most paints--it's not really an issue.
>
> > 4/ A glued structure has a waterproof glue line between parts.
> > Fasteners penetrate the waterproof joins.
>
> This is sorta true, but not true if your fastener goes in while the

glue

> is wet. And your fastener *should* be going in when the glue line is
> wet. Otherwise, what are you doing?
>

Hey, you're arguing with Michael Storer, not me, though I agree with
him. But on that last part, the screw penetrates through the glue
line, whenever you install it. Metal, having a different rate of
expansion, is going to work back and forth, and eventually it's going
to be easier for water to penetrate along a screw or ringnail,
especially if underwater, than from the outside of a glueline. Also,
above you mention "swelling of the wood"--which doesn't happen if no
water penetrates-- as a positive aspect of fasteners. If there's
enough moisture to swell the wood, sooner or later you'll get enough
decay to loosen the fastener.

>
> > 5/ Fasteners can make repairs difficult - where fasteners are
> > eliminated from the structure and part of the boat can be cut, planed
> > or sawn without risk of damaging tools
>
> True enough, although bronze and copper are only a modest hindrance.
>
>
> > I'd never considered points 3 and 4, but they make sense to me.
> > Another issue is that a glue joint spreads stresses over the largest
> > possible area, whereas fasteners tend to concentrate stresses.
>
> This is actually not correct. Keep in mind that a ring nail spreads

We'll have to disagree here. A fastener creates a point load. Just
consider the area secured by the head of a nail or screw. It's minute
compared to the area of a good wide glue joint. No matter how deeply
it penetrates the framing member, it's still only holding the planking
with its head. Remove the head and it's useless. Further, good
engineering practice designs joints that are glued in at least two
dimensions-- for example, the rub rail of my little cat is glued to
the topside planking, and then the side deck glues down over the sheer
clamp, the planking and the rub rail. Everything in that crucial
joint is secure in at least two dimensions except for the side deck,
but it's glued to a surface over two inches wide, and then glass taped
to cover the end grain and protect the rub rail. Fasteners would add
very little strength to that joint.

Of course, some joints can't be glued in two dimensions. Storer says
that, for example, rub rails not covered by the deck could be
fastened. So there are certainly still joints that may need
fastening. I'm probably going to use fasteners in the crossbeam to
web connections of my little cat, just because it could be
catastrophic if the glue line failed, (and probably because I lack
confidence in my boatbuilding skills.)

Consider that a ply boat built monocoque with epoxy is a composite
structure. Ask any cutting edge naval architect if he backs up his
high stress composite joints with fasteners and he'll look at you as
if you just landed from Mars. Again, point loads. Carbon composite
multihulls, which are probably the lightest and most highly stressed
boats in existence, use carbon fiber set in epoxy to transfer the
forces acting on crucial joints to the rest of the structure. As an
example of this thinking, there was recently a discussion on a
multihull group about forestay chainplates. Ian Farrier, the designer
of the Corsair F boats, stated that he no longer recommended bolted-on
chainplates, as composite chainplates made by wrapping glass or carbon
fiber around a thimble and gluing the fiber to the interior topsides
were stronger, cheaper, and would never leak or develop corrosion
problems.

Of course, all this is just my opinion. When boats were assembled
from pieces of timber and caulked with oakum, there was no choice.
You had to use fasteners. Maybe not any more. Michael Storer has
been building small boats without fasteners for decades and claims
he's never had one fall apart.

On the other hand, if you're not using epoxy, fasteners are probably
an excellent idea.

Ray

Robb

I still use stainless steel 1/4 crown staples. They hold nearly as well as screws and you can nail up a boat faster than you can even think about using nails

Message 3 of 21
, Nov 1, 2007

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I still use stainless steel 1/4 crown staples. They hold nearly as well as screws and you can nail up a boat faster than you can even think about using nails or screws. Robb

Ray wrote:
> True, but on the other hand, drywall screws are cheaper than stainless
> and reusable as temporary fasteners, and even if you use stainless
> screws, you still have to putty the heads to get a smooth hull.

I recommend against stainless--they are harder to use, and don't offer
much in most applications for Michalak-style boats. But if you got 'em,
you won't be much harmed by their use.

Drywall screws may be reusable, but they mangle up the wood a lot more
than they need to, and fairing the holes is, in fact, quite a job.

> Of the disadvantages of fasteners, he says:
> 1/ Fasteners are expensive

It's all relative. All the silicon bronze ring nails you'd need for,
say, a Philsboat should cost you less than $18 at Jamestown Distributors
(one pound of 3/4"). Cheaper if you use copper.

> 2/ Fasteners often make the boat a little bit harder to fair

Not really, considering the offset of fairing the marks made by either
the temporary drywall screws, or even the clamps used in place of any
fastening.

> 3/ Over time fasteners may move a little, cracking the paint that
> covers their heads and allow moisture to get in.

The paint line can separate between the nail head and the surface of the
wood, a very small amount. The swelling of the wood into the annular
rings provides a seal equal to most paints--it's not really an issue.

> 4/ A glued structure has a waterproof glue line between parts.
> Fasteners penetrate the waterproof joins.

This is sorta true, but not true if your fastener goes in while the glue
is wet. And your fastener *should* be going in when the glue line is
wet. Otherwise, what are you doing?

> 5/ Fasteners can make repairs difficult - where fasteners are
> eliminated from the structure and part of the boat can be cut, planed
> or sawn without risk of damaging tools

True enough, although bronze and copper are only a modest hindrance.

> I'd never considered points 3 and 4, but they make sense to me.
> Another issue is that a glue joint spreads stresses over the largest
> possible area, whereas fasteners tend to concentrate stresses.

This is actually not correct. Keep in mind that a ring nail spreads out
stresses compared to a glue line. A glue line puts stresses in only one
(or two) dimensions, whereas the fastener adds a second (or third)
dimension. This can be a real boon, particularly when you're attaching
a frame/bulkhead to the hull (which was the original situation that
started this discussion).

In short, in vessels designed with solid lumber/plywood joints,
fasteners can be an *excellent* strategy. They are no replacement in
joints designed for stitch-and-glue, but I don't think anyone was
recommending it.

-Chris

[Non-text portions of this message have been removed]

vexatious2001

... as well as screws and you can nail up a boat faster than you can even think about using nails or screws. Robb ... I need to get me a air staple gun (and a

as well as screws and you can nail up a boat faster than you can
even think about using nails or screws. Robb

>
>
>
>
>
>

I need to get me a air staple gun (and a new compressor
to replace the one I burned up) and try that some time.

Max

Rob Rohde-Szudy

I m with Max. No matter how good the glue is, I don t think it can ever replace a through fastener. It is immensely strong to use a metal piece that clamps the

Message 5 of 21
, Nov 1, 2007

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I'm with Max. No matter how good the glue is, I don't think it can ever replace a through fastener. It is immensely strong to use a metal piece that clamps the outside of one piece of wood all the way through to the opposite side of the other piece. Yes, epoxy joints usually break in the wood, which is good. Even better is having the wood itself reinforced with metal pins.

Like Max, just my opinion. And like Max I always seem to have one.

--Rob

Re: construction without fasteners

I vote for having the fasteners.

You almost have to have them anyway during "glue-up,"
and It's less work to use corrosion-resistant fasteners
and leave them in, than to use drywall screws and then
have to remove them and deal with the holes.

Just my opinion.

And I always have one.

__________________________________________________
Do You Yahoo!?
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[Non-text portions of this message have been removed]

Dave Gray

I m not totally sold on metal fasteners for all joint construction. Of late I ve been using bamboo skewers tipped with glue and driven into holes where screws

Message 6 of 21
, Nov 2, 2007

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I'm not totally sold on metal fasteners for all joint construction.
Of late I've been using bamboo skewers tipped with glue and driven
into holes where screws were used to help hold parts together
temporarily until the glue dried. After the glue dries, the glue
tipped skewers are driven into the holes. Later, the tops are clipped
off, then knocked down flush to the surface with a small jack plane.
Sure beats filling in over the tops of screws; and, for the cost of
about eight stainless screws, you can buy a package of 100 of these
skewers (50 larger diameter, 50 smaller diameter) at Wal-Mart that
fit nicely into #8 and #10 screw holes.

This approach works well on shear-stress joints. It may not be strong
enough for a joint where there is a poor fit or where joint strength
depends on one member being drawn up tightly to another under
tension. I still use bronze nails to hold a flat bottom to a frame,
for example.

>
>
> I'm with Max. No matter how good the glue is, I don't think it can

ever replace a through fastener. It is immensely strong to use a
metal piece that clamps the outside of one piece of wood all the way
through to the opposite side of the other piece. Yes, epoxy joints
usually break in the wood, which is good. Even better is having the
wood itself reinforced with metal pins.

>
> Like Max, just my opinion. And like Max I always seem to have one.
>
> --Rob
>
>
> Re: construction without fasteners
>
> I vote for having the fasteners.
>
> You almost have to have them anyway during "glue-up,"
> and It's less work to use corrosion-resistant fasteners
> and leave them in, than to use drywall screws and then
> have to remove them and deal with the holes.
>
> Just my opinion.
>
> And I always have one.
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
> [Non-text portions of this message have been removed]
>

pecostx@comcast.net

Just to be fecetious here, how about WAY back when they only used wooden pegs of different wood to swell up and fill the hole as fasteners? (hehehe) Geoff

Message 7 of 21
, Nov 2, 2007

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Just to be fecetious here, how about WAY back when they only used wooden pegs of different wood to swell up and fill the hole as fasteners? (hehehe)
Geoff
(just having a little fun here. although very little.)

> Drywall screws may be reusable, but they mangle up the wood a lot more
> than they need to, and fairing the holes is, in fact, quite a job.

It's probably one of those personal things, but I didn't find it to be
so. In other projects, when I used ring nails and screws, the holes
were just as big, because nails and screws should be set below the
surface, but the fairing putty tended to pop off sometimes because it
didn't get much of a grip on the heads. The trick to fairing the
empty screw holes, I find, is to use a low-density filler and mound it
up a bit. It only takes a second with the orbital sander to cut them
level.

>
> > Of the disadvantages of fasteners, he says:
> > 1/ Fasteners are expensive
>
> It's all relative. All the silicon bronze ring nails you'd need for,
> say, a Philsboat should cost you less than $18 at Jamestown
Distributors
> (one pound of 3/4"). Cheaper if you use copper.
>
>
> > 2/ Fasteners often make the boat a little bit harder to fair
>
> Not really, considering the offset of fairing the marks made by either
> the temporary drywall screws, or even the clamps used in place of any
> fastening.
>
> > 3/ Over time fasteners may move a little, cracking the paint that
> > covers their heads and allow moisture to get in.
>
> The paint line can separate between the nail head and the surface of
the
> wood, a very small amount. The swelling of the wood into the annular
> rings provides a seal equal to most paints--it's not really an issue.
>
> > 4/ A glued structure has a waterproof glue line between parts.
> > Fasteners penetrate the waterproof joins.
>
> This is sorta true, but not true if your fastener goes in while the
glue
> is wet. And your fastener *should* be going in when the glue line is
> wet. Otherwise, what are you doing?
>

Hey, you're arguing with Michael Storer, not me, though I agree with
him. But on that last part, the screw penetrates through the glue
line, whenever you install it. Metal, having a different rate of
expansion, is going to work back and forth, and eventually it's going
to be easier for water to penetrate along a screw or ringnail,
especially if underwater, than from the outside of a glueline. Also,
above you mention "swelling of the wood"--which doesn't happen if no
water penetrates-- as a positive aspect of fasteners. If there's
enough moisture to swell the wood, sooner or later you'll get enough
decay to loosen the fastener.

>
> > 5/ Fasteners can make repairs difficult - where fasteners are
> > eliminated from the structure and part of the boat can be cut, planed
> > or sawn without risk of damaging tools
>
> True enough, although bronze and copper are only a modest hindrance.
>
>
> > I'd never considered points 3 and 4, but they make sense to me.
> > Another issue is that a glue joint spreads stresses over the largest
> > possible area, whereas fasteners tend to concentrate stresses.
>
> This is actually not correct. Keep in mind that a ring nail spreads
out
> stresses compared to a glue line. A glue line puts stresses in only
one
> (or two) dimensions, whereas the fastener adds a second (or third)
> dimension.

We'll have to disagree here. A fastener creates a point load. Just
consider the area secured by the head of a nail or screw. It's minute
compared to the area of a good wide glue joint. No matter how deeply
it penetrates the framing member, it's still only holding the planking
with its head. Remove the head and it's useless. Further, good
engineering practice designs joints that are glued in at least two
dimensions-- for example, the rub rail of my little cat is glued to
the topside planking, and then the side deck glues down over the sheer
clamp, the planking and the rub rail. Everything in that crucial
joint is secure in at least two dimensions except for the side deck,
but it's glued to a surface over two inches wide, and then glass taped
to cover the end grain and protect the rub rail. Fasteners would add
very little strength to that joint.

Of course, some joints can't be glued in two dimensions. Storer says
that, for example, rub rails not covered by the deck could be
fastened. So there are certainly still joints that may need
fastening. I'm probably going to use fasteners in the crossbeam to
web connections of my little cat, just because it could be
catastrophic if the glue line failed, (and probably because I lack
confidence in my boatbuilding skills.)

Consider that a ply boat built monocoque with epoxy is a composite
structure. Ask any cutting edge naval architect if he backs up his
high stress composite joints with fasteners and he'll look at you as
if you just landed from Mars. Again, point loads. Carbon composite
multihulls, which are probably the lightest and most highly stressed
boats in existence, use carbon fiber set in epoxy to transfer the
forces acting on crucial joints to the rest of the structure. As an
example of this thinking, there was recently a discussion on a
multihull group about forestay chainplates. Ian Farrier, the designer
of the Corsair F boats, stated that he no longer recommended bolted-on
chainplates, as composite chainplates made by wrapping glass or carbon
fiber around a thimble and gluing the fiber to the interior topsides
were stronger, cheaper, and would never leak or develop corrosion
problems.

Of course, all this is just my opinion. When boats were assembled
from pieces of timber and caulked with oakum, there was no choice.
You had to use fasteners. Maybe not any more. Michael Storer has
been building small boats without fasteners for decades and claims
he's never had one fall apart.

On the other hand, if you're not using epoxy, fasteners are probably
an excellent idea.

Ray

[Non-text portions of this message have been removed]

Kenneth Grome

... Do you mean like three years ago? http://www.naga-pelangi.de/Naga_2/album/may04SPF/page36.html http://www.naga-pelangi.de/Naga_2/album/may04SPF/page37.html

Message 8 of 21
, Nov 2, 2007

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> Just to be fecetious here, how about WAY back
> when they only used wooden pegs of different
> wood to swell up and fill the hole as fasteners?

... My comment was generic, not personal. The you was directed toward someone who is building a boat, and fastening plywood to a solid lumber frame without

Message 9 of 21
, Nov 2, 2007

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I wrote:

>> And your fastener *should* be going in when the glue line is
>> wet. Otherwise, what are you doing?

Ray writes:

> Hey, you're arguing with Michael Storer, not me, though I agree with
> him. But on that last part, the screw penetrates through the glue
> line, whenever you install it. Metal, having a different rate of
> expansion, is going to work back and forth, and eventually it's going
> to be easier for water to penetrate along a screw or ringnail,
> especially if underwater, than from the outside of a glueline. Also,
> above you mention "swelling of the wood"--which doesn't happen if no
> water penetrates-- as a positive aspect of fasteners. If there's
> enough moisture to swell the wood, sooner or later you'll get enough
> decay to loosen the fastener.

My comment was generic, not personal. The "you" was directed toward
someone who is building a boat, and fastening plywood to a solid lumber
frame without glue--"what is that person doing?" And the answer is
probably screwing up.

Wood does not require moisture to swell around an annular ring nail. It
is inherent in the qualities of most boatbuilding woods to swell around
the annular rings--all softwoods will do so (and who builds bulkheads of
Michalak boats without softwoods? People who are not sensible.).

> We'll have to disagree here. A fastener creates a point load. Just
> consider the area secured by the head of a nail or screw. It's minute
> compared to the area of a good wide glue joint. No matter how deeply
> it penetrates the framing member, it's still only holding the planking
> with its head. Remove the head and it's useless.

First off, you're exaggerating here. An annular nail has "gripping
power" along most of its shaft. You example/complaint only applies when
the plywood is so thin that it is thinner than the part of the nail near
the head with no rings. Second of all, no one was suggesting that one
would fail to use glue, the recommendation I was making was clearly *in
addition* to a glue line. Third, you're resisting the main point of the
argument--a nail offers compression (where the head is essential, as you
point out) *and* shear resistance, which is much, much more important,
and works absolutely fine in the absence of a head--the shaft alone
does the majority of the work.

> Consider that a ply boat built monocoque with epoxy is a composite
> structure. Ask any cutting edge naval architect if he backs up his
> high stress composite joints with fasteners and he'll look at you as
> if you just landed from Mars. Again, point loads.

You seem to be making a point in opposition to something, but I don't
know what. I wrote "They [fasteners] are no replacement in joints
designed for stitch-and-glue, but I don't think anyone was
recommending it." So apparently you're agreeing with me?

rhaldridge

... bulkheads of ... Perhaps you were referring to springback here-- the tendency of ruptured wood to return to its original shape. Most boatbuilders, when

>
> Wood does not require moisture to swell around an annular ring nail. It
> is inherent in the qualities of most boatbuilding woods to swell around
> the annular rings--all softwoods will do so (and who builds

bulkheads of

> Michalak boats without softwoods? People who are not sensible.).

Perhaps you were referring to springback here-- the tendency of
ruptured wood to return to its original shape. Most boatbuilders,
when speaking of "swelling" would be referring to the tendency of wet
wood to swell, as in a carvel planked boat that must be kept wet to
swell the planks enough to tighten the caulking.

>
> > We'll have to disagree here. A fastener creates a point load. Just
> > consider the area secured by the head of a nail or screw. It's minute
> > compared to the area of a good wide glue joint. No matter how deeply
> > it penetrates the framing member, it's still only holding the planking
> > with its head. Remove the head and it's useless.
>
> First off, you're exaggerating here. An annular nail has "gripping
> power" along most of its shaft. You example/complaint only applies when
> the plywood is so thin that it is thinner than the part of the nail

near

> the head with no rings.

Okay, so let's nail two pieces of wood together with a headless
ringnail. It will have some resistance to being peeled apart, but not
enough that I couldn't pull it apart, given a few inches of leverage.
I've pulled a lot of ringnails out with vicegrips (I'm not a very
good boatbuilder) It's true it would have a lot of resistance to
shear, but it has none at all to torsion. A good glue joint does,
because it spreads its holding power over a larger area. And 1/4"
planking, common on small boats, has almost no resistance to peeling
forces, if secured by a headless nail.

Second of all, no one was suggesting that one

> would fail to use glue, the recommendation I was making was clearly *in
> addition* to a glue line.

The point I'm trying to get across is that in many instances, the
amount of security added by fasteners to a good glue joint is not
enough to be worth the trouble.

Third, you're resisting the main point of the

> argument--a nail offers compression (where the head is essential, as

you

> point out) *and* shear resistance, which is much, much more important,
> and works absolutely fine in the absence of a head--the shaft alone
> does the majority of the work.

Most screws and ringnails are used to secure planking to a framework.
Shear is not much of an issue under those circumstances. Long before
a nail could contribute to preventing shear forces from moving a
planking panel, almost all the glue lines holding the planking to the
frame would have to be broken. This seems to me a pretty good
illustration of why permanent fasteners are redundant in a ply-epoxy
boat.

>
> > Consider that a ply boat built monocoque with epoxy is a composite
> > structure. Ask any cutting edge naval architect if he backs up his
> > high stress composite joints with fasteners and he'll look at you as
> > if you just landed from Mars. Again, point loads.
>
> You seem to be making a point in opposition to something, but I don't
> know what.

I thought you were saying that epoxy-wood joints should be backed up
with fasteners. If a composite engineer wouldn't do it (point loads!)
why do you think it is a good idea?

I wrote "They [fasteners] are no replacement in joints

> designed for stitch-and-glue, but I don't think anyone was
> recommending it." So apparently you're agreeing with me?
>

It doesn't sound like it, does it? I'll try again. Your point seems
to be that permanent fasteners are a good idea, even in the presence
of a good glue joint. My point is that they add little actual
strength to a good glue joint, and may pose potential problems (point
loads, a path for water migration, complicating repairs, etc.), so why
use them?

Did you happen to look at the link I gave to Michael Storer's site?
He shows pictures of a Goat Island Skiff built many years ago without
fasteners. It's never been repainted and it looks like new.

To be fair, I'll probably never build a boat to that standard. The
GIS was painted with linear polyurethane, and my little cat is being
painted with house paint. He has glass both sides of every surface
and my cat is only glassed to the waterline on the outside. But I'm
not averse to learning from better boatbuilders than I'll ever be (a
category that, unfortunately, includes almost everyone.)

Michael Storer is a very good boatbuilder and his arguments seem
pretty good to me. If they don't to you, so what? In a hundred years
it won't make a bit of difference.

Ray

Chris Crandall

Michalak@yahoogroups.com ... So, we agree. You ve qualified your poitn with in many instances and on that point, we agree. You ve not stated without

> The point I'm trying to get across is that in many instances, the
> amount of security added by fasteners to a good glue joint is not
> enough to be worth the trouble.

So, we agree. You've qualified your poitn with "in many instances" and
on that point, we agree. You've not stated without qualification,
implying that, in some instances, it is a good idea. And that is,
*exactly* my point. The particular case, which I've vbeen discussing
all along, and which the argument has had a tendency to stray from, is
the frame to planking joint, plywood to solid softwood lumber.

> Most screws and ringnails are used to secure planking to a framework.
> Shear is not much of an issue under those circumstances.

We'll have to disagree. A solid collision of a hull along the gunwales
will cause shear between frame and skin in a lot of circumstances, often
not in the place of location, but in a spot elsewhere, such as on the
other side of the boat.

> I thought you were saying that epoxy-wood joints should be backed up
> with fasteners. If a composite engineer wouldn't do it (point loads!)
> why do you think it is a good idea?

No, I was saying that *some* joints should be--the specific one that
started the discussion. It doesn't add much value to straw-man the argument.

> Did you happen to look at the link I gave to Michael Storer's site?

I've been there before, but not since this discussion.

> To be fair, I'll probably never build a boat to that standard. The
> GIS was painted with linear polyurethane, and my little cat is being
> painted with house paint. He has glass both sides of every surface
> and my cat is only glassed to the waterline on the outside. But I'm
> not averse to learning from better boatbuilders than I'll ever be (a
> category that, unfortunately, includes almost everyone.)

A double-epoxy/glass skinned boat is an entirely different animal from
the Michalak-style construction we (mostly) talk about in this forum.
The engineering is quite different, as Jacques Mertens has so generously
explained.
See http://www.bateau.com/ or any number of posts on rec.boats.building

> Michael Storer is a very good boatbuilder and his arguments seem
> pretty good to me. If they don't to you, so what? In a hundred years
> it won't make a bit of difference.

In 100 years GW Bush won't be President either, but it seems important
'round about now.

Cheers!

-Chris

rhaldridge

... often ... I m afraid I ll have to admit that I don t understand this. That sounds like a buckling load to me-- displacement would primarily be lateral,

>
> We'll have to disagree. A solid collision of a hull along the gunwales
> will cause shear between frame and skin in a lot of circumstances,

often

> not in the place of location, but in a spot elsewhere, such as on the
> other side of the boat.

I'm afraid I'll have to admit that I don't understand this. That
sounds like a buckling load to me-- displacement would primarily be
lateral, not in shear. In any case, if the loads are in fact in
shear, then for the fasteners to have any effect on keeping the
planking in place, a lot of glue lines will have to let go, and we're
back to the point load problem. A nail or screw resisting enough shear
to pop a lot of glue lines will be displaced to some extent, opening
up a path for water penetration.

>
> > I thought you were saying that epoxy-wood joints should be backed up
> > with fasteners. If a composite engineer wouldn't do it (point loads!)
> > why do you think it is a good idea?
>
> No, I was saying that *some* joints should be--the specific one that
> started the discussion. It doesn't add much value to straw-man the

argument.

Could you explain how this is a strawman argument? You've said that a
wood epoxy joint (planking to frame) should be backed up by fasteners.
Is it that you don't define that as a composite joint?

>
> A double-epoxy/glass skinned boat is an entirely different animal from
> the Michalak-style construction we (mostly) talk about in this forum.
> The engineering is quite different, as Jacques Mertens has so

Are you saying that fasteners are unnecessary in planking a
double-skinned boat? I wonder how your arguments as to shear forces
would differ in discussing such construction.

>
> > Michael Storer is a very good boatbuilder and his arguments seem
> > pretty good to me. If they don't to you, so what? In a hundred years
> > it won't make a bit of difference.
>
> In 100 years GW Bush won't be President either, but it seems important
> 'round about now.
>

I think you have just illuminated the difference between a trivial
problem and a serious problem.

Just to be clear, using fasteners (or not) in small boats falls into
the former category.

I'm going to have to let this go, I think. But if I end up floating
in the bay, clinging to the remnants of my fallen-apart cat, I'll
remember that you told me so.

Ray

pgochnour@aol.com

Ray and Chris....great discussion..interesting and informative....hope you two will find another subject about which to disagree in the very near future...

Message 13 of 21
, Nov 4, 2007

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Ray and Chris....great discussion..interesting and informative....hope you
two will find another subject about which to disagree in the very near
future...

We re close, but with a few small areas of disagreement. I ll edit it down, and see if we end up on the same page. This exchange is critical. ... Ray: Could

Message 14 of 21
, Nov 5, 2007

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We're close, but with a few small areas of disagreement. I'll edit it
down, and see if we end up on the same page.

This exchange is critical.

Ray:

>>> I thought you were saying that epoxy-wood joints should be backed up
>>> with fasteners. If a composite engineer wouldn't do it (point loads!)
>>> why do you think it is a good idea?

Chris:

>> No, I was saying that *some* joints should be--the specific one that
>> started the discussion. It doesn't add much value to straw-man the
> argument.

Ray:> Could you explain how this is a strawman argument? You've said that a

> wood epoxy joint (planking to frame) should be backed up by fasteners.
> Is it that you don't define that as a composite joint?

A glued wood joint, even with epoxy, is not a composite joint.
Composite materials, in everyday boatbuilding parlance, almost always
refers to "fabric set in resin." A joint that is plywood to solid
lumber, using epoxy, is not a composite joint, it's just glued up.

In such a case, I recommend fasteners (and not just one!).

Now a joint that joins, say, a plywood bulkhead, without solid wood
framing around it, to a plywood hull, using thickened epoxy and a lay-up
of fiberglass or other epoxy-friendly fabric (usually with a spacer to
prevent the formation of a hard spot) would be a composite joint, and in
such a case, fasteners should be eschewed.

Chris:

>> A double-epoxy/glass skinned boat is an entirely different animal from
>> the Michalak-style construction we (mostly) talk about in this forum.
>> The engineering is quite different, as Jacques Mertens has so
>> generously explained. See http://www.bateau.com/

Ray:

> Are you saying that fasteners are unnecessary in planking a
> double-skinned boat? I wonder how your arguments as to shear forces
> would differ in discussing such construction.

I would say that, in *some* double-skinned boats, fasteners are
unnecessary. However, that is not how Michalak engineers his boats, or
at least any of the boats I've seen plans for or built.

> I'm going to have to let this go, I think. But if I end up floating
> in the bay, clinging to the remnants of my fallen-apart cat, I'll
> remember that you told me so.
> Ray

I think that it's unlikely that you'll experience catastrophic failure.
But I *have* experienced failure of such a joint, and I regret not using
a handful of nails to solve exactly this problem. The boat still is
usable, but the fix was harder than the solution would have been if I'd
used nails from the outset.

-Chris

pecostx@comcast.net

I agree also. That poor horse has been beaten to death for a few days too many in my opinion and like Max I ve got mine. Geoff ... From: pgochnour@aol.com Ray

Message 15 of 21
, Nov 5, 2007

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I agree also. That poor horse has been beaten to death for a few days too many in my opinion and like Max I've got mine.

Geoff

-------------- Original message --------------
From: pgochnour@...
Ray and Chris....great discussion..interesting and informative....hope you
two will find another subject about which to disagree in the very near
future...